Medical laboratories process and analyze hundreds of biological samples each day. Typically, the process and analysis of these samples involves placing a sample in a cuvette with a particular solution and then subjecting the sample to a photometric analysis. Once the testing is completed, the cuvette with the analyzed sample is discarded. To process and analyze more samples each day, laboratories have sought ways to handle cuvettes more quickly (i.e. to handle more cuvettes within a given unit of time).
To increase cuvette throughput, and to decrease labor costs, medical laboratories have become increasingly automated. Thus, cuvettes have been mounted on a conveyor and passed through one or more fill stations and one or more analysis stations before being passed to a disposal station, the entire operation being computer controlled. However, one area of the operation which has proved difficult to automate has been the feeding of cuvettes in the conveyor.
The small size, irregular shape and delicate nature of the cuvettes makes them difficult to handle quickly while still having each cuvette precisely oriented in the conveyor. More particularly, each cuvette comprises one or more small riles or wells, typically formed of plastic or glass, which may be joined together at one end. The inside of each cuvette must be kept clear from contamination and the outside of each cuvette, at least in the area where photometric analysis is to be performed, must be kept clear from scratches. Cuvettes which are contaminated or damaged cannot be used.
The current technique generally employed for feeding cuvettes to a conveyor is an automated hopper system. Such a system has a hopper in which the cuvettes are loaded. Once loaded, the hopper is spun, vibrated or otherwise agitated to jostle the cuvettes into a desired orientation. The hopper has a drop slot located over the conveyor which is shaped to only permit properly oriented cuvettes to pass through. When a cuvette is jostled into a properly oriented position over the slot, the cuvette drops through onto the conveyor belt.
Such hopper systems have a number of problems. First, the feeding of cuvettes is somewhat random, limiting the predictable feed rate of the system. Second, the cuvettes in the hoppers are frequently contaminated by dust and dirt which accumulates in the hopper. Third, the cuvettes in the hopper are frequently scratched from the jostling between cuvettes during agitation. Fourth, such jostling can also cause cuvettes to break, such breaks frequently causing the system to jam. Finally, the cuvettes in a hopper have a tendency to pick up static electricity, which causes the cuvettes to stick to the walls of the system and also causes jams.
Problems such as those described above can also arise in other situations, such as in automated assembly of products, where it is desired to feed small, irregular, and fragile parts or other objects onto a conveyor.
Another technique currently employed for supplying cuvettes to a medical instrument is to mount 20 to 100 in a circular tray which is installed in the instrument by an operator at the beginning of each run. The trays used in this technique add a large amount of biocontaminated plastic to the waste stream, significantly increasing disposal costs. This technique can also waste time and/or cuvettes, particularly in the situation where the operator has only a few unused cuvettes left in the current tray and wants to start a large run. The operator either has to come back to the instrument in a few minutes or discard the unused cuvettes.
Accordingly, an object of this invention is to provide a system for more rapidly and reliably feeding objects to a conveyor.
A more specific object of this invention is to provide a cuvette feeder system which minimizes the number of cuvettes wasted by among other things minimizing the possible contamination of cuvettes and minimizing possible damage to the cuvettes.
Another object of this invention is to provide a cuvette feeder system which minimizes jams caused by mechanical failures, static electricity buildup, cuvette breakage and random error.
Another object of this invention is to provide a system for feeding objects to a conveyor, which system is easy to load and operate, including improved apparatus for use in such system.
Other objects and advantages will become apparent from the following description of the invention.